Page:Popular Science Monthly Volume 13.djvu/709

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is actually accomplished by the operations which I have here disclosed.

A certain organic substance expands under chemical composition, and afterward contracts under chemical decomposition. Its disintegration is incited by the dynamical influences of the medium; its reintegration is brought about by its own inherent chemical affinity, which affinitive power effects its combination with complemental material furnished by the medium.

In pursuing the inquiry here begun, the next step would be to show how complications of these sundry phases of the one central fact of motility lead to definite organization in various directions, and to the rise of sensation.



THE great development of electricity in thunder-storms has been a subject of much speculation. Its explanation, however, is still an unsettled question. Some views on this subject are presented in this paper.

We have no evidence that the production of fogs or clouds—the change from invisible to visible vapor, or from combined to uncombined moisture—produces any electricity. All experiments to establish such a supposition have had a negative result.

These particles of vapor we may suppose to be small spherules, each with its normal portion of electricity that surrounds or occupies the surface of the sphere. When two of these particles unite and form one, the combined particle will have twice the electricity of either of the separate parts, but not twice the surface. There will then be an accumulation of electricity upon the surface of the combined particle; and still more will this be so when thousands of these spherules unite to form a drop of water.

We may well conceive, therefore, that a cloud forming water should become surcharged with electricity, that will escape in violent explosions when the accumulation is too rapid or the circumstances are unfavorable to its being carried off by the surrounding moist air.

It is not, then, the formation of vapor, but its condensation to rain, that produces thunder and lightning. And this, it is believed, accords with all our experience. Clouds are constantly forming and disappearing; fogs and vapors are accumulated in some places in great abundance, but no electrical excitement has ever been observed. But, on the other hand, there is never a flash of lightning without a manifest

  1. Paper read before the Philosophical Society of Washington.